Virtually every city in the United States, as well as in foreign countries, has sanitary drainage systems and sewage disposal systems. A vast network of underground pipes is effective to carry the waste water and sewage to the respective disposal systems. The underground piping systems are generally constructed of concrete, clay or metal pipes which have a lifetime of many years. However, such piping systems do not last indefinitely. There are many external influences which can reduce the lifetime of such piping systems. For example, an accumulation of acids from the formation of hydrogen sulfide gas in the sewer attacks the material in concrete and asbestos cement pipes. The gases condense on the upper internal surface of the pipe and the resulting acids can deteriorate the pipe so that holes are eventually formed through the sidewalls, or the pipe becomes so porous that it is weakened and easily crumbles. While clay tile is generally not affected by the hydrogen sulfide gas or acids, the quality of the clay used to fabricate the clay tile can be of such inferior quality that the life of the pipe is greatly reduced. Metal pipes can be subject to corrosive action and breakage. Further, the sealed ends of any of these types of pipes can become defective over time, thereby allowing roots to grow therein. As the roots grow in size, the pipes become separated and allow sewage or waste water to leak into the surrounding soil. The movement of the soil such as by frost, shifting or earthquakes is another mechanism which can cause leaks in the piping system.
A recent concern of the integrity of the national underground piping systems is that of the environment affected by the piping system. Numerous environmental regulations have been implemented to control the integrity of the underground piping systems to preserve the quality of the water, air and soil. In view of the foregoing, a substantial concern has been generated over the quality of the present underground piping systems throughout the United States, and techniques for replacing the same due to the age or deterioration of the pipes themselves or entire systems.
Various techniques and apparatus have been developed for addressing the problem of replacing underground pipes, and especially sewer pipes. A major concern for the replacement of underground pipes is that of minimizing the disturbance of private or public property in replacing the pipes. For example, while the trenching or digging with a backhoe is effective to expose the old underground pipes for repair or replacement, such technique is extremely invasive and disturbing of the soil owned by the property owners. Furthermore, such replacement techniques are time consuming and thus represent a substantial interruption in the service to the customers using the underground pipes. To circumvent many of these problems, many techniques and devices have been developed for pulling a "mole" through the old piping system to break it up and provide a channel through which a new pipe is pulled. U.S. Pat. No. 4,983,071 by Fisk, et al. discloses a pipe bursting apparatus which is pulled through the old pipe to break it up, and new pipe attached to the bursting equipment is simultaneously pulled and thus installed in the path of the old pipe. This system requires a cable to be initially routed through the old pipe system and connected to a conical element for pulling through the old system and bursting the pipe. Connected to the conical element is a new plastic pipe which is pulled by the equipment and automatically routed in the path of the old system. U.S. Pat. No. 5,076,731 by Luksch discloses an element that is pulled through the old piping system to form an enlarged bore so that a correspondingly larger new pipe can be installed in lieu of the old pipe. In U.S. Pat. No. 4,930,542 by Winkle, et al., there is disclosed an underground pipe restoring technique for pushing new sections of pipe in the path of the old pipe. In the Winkle, et al. system, a frontal part of the apparatus is hydraulically operated to expand radially outwardly and break up the tile. Once the old tile is broken, a hydraulic ram in the back section pushes the new pipe sections forwardly, as well as pushes the frontal section forwardly into the old pipe, and thereafter the frontal element is again actuated to expand radially outwardly and break up the old pipe.
In many of the techniques disclosed in the prior art, the pipe bursting element must be pulled by a cable through the old pipe system. The disadvantage of such a technique is that the cable must be initially routed through the old pipe system, which effort can be extremely difficult if the old pipe system is broken and dirt or debris has otherwise fallen into the pipe. Further, an extremely large area must be dug into the soil at the distant end to provide room for pulling equipment, such as a winch. The prior art also includes pipe bursting equipment that is very complicated and expensive and subject to breakage or inoperability when soil or pieces of broken pipe fall into the mechanism.
From the foregoing, it can be seen a need exists for a new technique and apparatus for replacing underground piping systems without disturbing the surface soil and which can be carried out efficiently and reliably. A further need exists for a technique that can be operated in a manhole to replace old deteriorated pipes extending therefrom. Yet another need exists for a technique for replacing old underground pipes with new clay tile sections by pushing the new clay tile sections into the path of the old pipe. These and other needs are met by the features and advantages of the invention which are described in detail below.